Karoo System

Karoo System, also spelled Karroo, geologic system of rocks outcropping over a 1,560,000-square-kilometre (600,000-square-mile) area of Africa from the Equator south to the Cape of Good Hope. The time span of the Karoo System extends from the Carboniferous and Permian periods (about 359 million to 251 million years ago) to the Late Triassic Epoch (about 229 million to 200 million years ago). At its thickest, the Karoo consists of more than 10,500 m (35,000 feet) of rocks. The presence of coal seams, along with some petroleum, makes it commercially important. Of scientific interest is the almost singular glimpse the Karoo affords of reptilian life, especially the mammallike therapsid reptiles, among whose ranks are to be found the progenitors of the true mammals.

The Karoo System is subdivided into four series, which from youngest to oldest are the Stormberg Series (Late Triassic), Beaufort Series (Late Permian–Early Triassic), Ecca Series (Early Permian), and Dwyka Series (Early Permian).

Karoo sediments are nonmarine and consist of shales, red beds, siltstones, and great quantities of volcanics. The flora and fauna of the Karoo are terrestrial and appear to record a gradual climatic shift toward ever-increasing aridity. Glacial deposits in the Dwyka Series are matched by contemporaneous deposits in South America, India, and Australia.

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any member of the class Reptilia, the group of air-breathing vertebrates that have internal fertilization, amniotic development, and epidermal scales covering part or all of their body. The major groups of living reptiles—the turtles (order Testudines), tuatara (order Rhynchocephalia...

...of the country, dominating the topography; it is separated from surrounding areas of generally lower elevation by the Great Escarpment. The plateau consists almost entirely of very old rock of the Karoo System, which formed from the Late Carboniferous Epoch (about 320 to 300 million years ago) to the Late Triassic Epoch (about 230 to 200 million years...

...of the Katangan Complex (about 620 million years old) are extensive in the central areas, and mineralization of these rocks is the basis of Zambia’s mining industry. Later sedimentary rocks of the Karoo (Karroo) System filled rifted troughs in the plateau surface, some of which, as in the Luangwa and middle Zambezi valleys, have been partially re-excavated. Coal seams occur in Karoo rocks to...